use source std on stage 0 for opt-dist

Signed-off-by: onur-ozkan <work@onurozkan.dev>

src/tools/opt-dist/src/exec.rs

@@ -109,6 +109,8 @@ impl Bootstrap {
             "--stage",
             "2",
             "library/std",
+            // FIXME: benchmarks fails when using beta std on stage 0
+            "--build-std-on-stage0",
         ])
         .env("RUST_BACKTRACE", "full");
         Self { cmd, metrics_path }